New-Tech Europe Magazine | June 2018

Figure 5. 2MHz 5V/2A application using the LT8609S.

regulator on a 2-layer board. The integrated MOSFETs and built-in compensation circuit of the LT8609S reduce the component count to the device itself plus a few external components. Together with the high speed switching frequency, the total core solution size for this typical application is only 11.5mm × 12.3mm. One way to reduce solution costs is to minimize the number of required PCB layers, but performance trade-offs are expected. For instance, a 2-layer board solution is not expected to produce equivalent EMI performance to a 4-layer solution. EMI results in Figure 7 show that the LT8609S on a 2-layer board satisfies CISPR 25 Class 5 EMI emissions. EMI performance is Figure 6. Small solution size of the LT8609S 2-layer board

faster dynamic responses with proper loop compensation. Figure 2 shows the proper component values. It is also critical in board layout to minimize trace inductance from the output capacitors of the circuit to the load. Figure 4 shows the transient test results of the solution shown in Figure 2. High Efficiency, Compact Solution For Lower Power Applications In addition to the low voltage high current applications such as SOC and CPU, automobiles and other vehicles require power for numerous low cur-rent loads, such as dashboard instrument clusters, heads up displays, V2X, sensors, USB chargers, etc.

Due to the limited space and limited battery power, high efficiency and small solution size are top requirements for power converters. Low noise is a given. LT8609S is a suitable solution for all these applications. It’s designed with 3V to 42V input voltage range for automotive battery conditions. Integrated MOSFETs, built- in compensation circuit and 2MHz operation frequency minimize the LT8609S solution size. Silent Switcher 2 technolo-gy and integrated hot loop capacitors are used in the LT8609S to minimize noise levels and provide exceptional efficiency as well as excellent EMI performance. Figure 5 shows a 2MHz, 5V/2A application using LT8609S. Figure 6 shows a complete LT8609S

Figure 7. (a) Average radiated EMI test results of the LT8609S on a 2-layer board showing results with spread spectrum frequency modulation enabled for further EMI reduction. (b) Peak radiated EMI performance comparison between 2- and 4-layer boards with the LT8609S.

Figure 8. Thermal performance comparison between 2-layer and 4-layer boards with LT8609S.

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